Each subject was diagnosed by a physical therapist as having PFPS for which she had not previously been treated. The diagnostic criteria for PFPS were those described by Fulkerson and Hungerford.' The subjects'painful knees were tapedn so that their symptoms were reduced immediately by at least 50%, as rated by the subjects during a one-leg squat pain provocation test.Subjects were excluded if they had had any knee surgery. To reduce the possible confounding effect of pain during the activity, subjects were also excluded if they experienced pain that visibly altered their kinematics when they walked up and down stairs or if they reported
difficulty in walking up and down stairs without patellar taping.